Field of Invention
The present invention relates to a field of building materials, and more particularly to a cathode protection method of embedded CFRP anode for a reinforced concrete structure. And, the present invention further relates to a composite structure and a processing method for reinforced concrete structure with a cathode protection CFRP structure.
Description of Related Arts
The main reason for the eroding durability of the deterioration of the reinforced concrete structure is the internal corrosion of the steel reinforcing element. Currently, the impressed current cathode protection technology has proven to be one of the most effective methods to inhibit the corrosion of the steel reinforcing element. The impressed current cathode protection technology is based on the principle of the PH-potential diagram, wherein cathode current is applied to the steel reinforcing element for forcing the potential of the steel reinforcing element in the corrosion-free area so as to reach the protection purpose for the steel reinforcing element.
Accordingly, an auxiliary anode is one of the most important parts in the impressed current cathode protection technology. One of the existing auxiliary anode structures is that the auxiliary anode is tiled in pieces on a surface of the structure of the steel reinforcing element, and the other auxiliary anode structure is that the auxiliary anode is spacedly affixed into a pre-designed preformed grooves, wherein these two structures of the existing auxiliary anode are related to the structure of the protection area and the resistance of the concrete. The auxiliary anode of the first auxiliary anode structure is widely coved on the surface of the structure of the steel reinforcing element, wherein the auxiliary anode has the larger coverage area so as to facilitate the distribution of the current, but it is also limited by the effects of the non-uniform resistance of concrete, such as a mixed metal titanium oxide anode. The auxiliary anode of the second auxiliary anode structure as mentioned above is that the auxiliary anode is spacedly affixed in the preformed grooves of the structure of the steel reinforcing element, wherein the coverage area of the auxiliary anode is relative small which means the distribution of the current is relatively weak, but this manner reduces the distance between the steel reinforcing element and the concrete so as to reduce the resistance therebetween, such as the buried-type anode. Furthermore, the concrete is a heterogeneous material, and has great resistance and uneven in distribution, such that the concrete is easy to be affected by the environmental factors.
In the present technology, according to the perspective of the material science, the use of a steel, fiber-reinforced polymer (referred to as FRP) or carbon fiber reinforced polymer (CFRP) are utilized to process structural steel reinforcing element and bonding materials. However, the construction process has several defects and errors; any deterioration during the construction process will destroy this protective layer (structural strengthening materials) so as to cause the secondary corrosion of the concrete.
In recent years, FRP-concrete composite structures are increasingly attracted by the attention of scholars. This is because FRP-concrete composite structure can improve the force situation, wherein the FRP are templates in the construction process, so no additional templates and no corresponding template removal steps are needed, such that the FRP has an excellent durability. A Good durability of the FRP-concrete composite structure is mainly due to the use of good durability of the FRP, and the FRP has the ability to prevent intrusion of external harmful substances in a member while FRP is overall wrapped on that member. The structural durability is more sensitive to the required of the materials, the construction process and the working environment. When an improper construction step happened, the durability of the FRP-concrete composite structure will no longer have the advantages due to the internal defects of the FRP materials and plenty of harmful substances which contain therein. While using concrete with rich of chlorides, sulfates and other harmful substances, such as sand type concrete, the concrete has various conditions of the acceleration of the corrosion of steel reinforcing element, so the corrosion of the steel reinforcing element within the FRP-concrete composite structure occurs more earlier, wherein the durability of the FRP-concrete composite structure is damaged, so the FRP-concrete composite structure need to be repaired and maintained early.
The most common structural strengthening materials in the structural strengthening field and the composite structure field are carbon fiber reinforced polymer (CFRP), which has the advantages of light in weight, high in strength, high in modulus, and having good corrosion resistance, so CFRP is a well-known structural strengthening material. Including the well-known dynamic properties of CFRP, its essential element, carbon fibers, has good electrochemical properties, which has good electrical conductivity and the electrode potential is close to the electrochemical property of the noble metal. Therefore, the electrochemical properties of the CFRP can be applied to the auxiliary anode of the impressed current cathode protection system for the reinforced concrete structures. And, the electrochemical properties and the dynamic properties of the CFRP also can be applied to form a new type composite structure for reinforced concrete structure with a good durability.
Furthermore, the electrochemical properties and the dynamic properties of the CFRP also can be applied to form a new type composite structure for reinforced concrete structure having steel reinforcing element protection and cathode protection. The CFRP, as a composite material in the structure, not only has advantages in the composite structure, but also is an auxiliary anode in the impressed current cathode protection system. The weak cathode current is applied to the CFRP-composite structure while the structure starts to be built, and the steel reinforcing element in the CFRP-composite structure is in a cathode polarization situation for a long time, so as to achieve the protection effect. Therefore, the CFRP-composite structure has a strong ability to resist the corrosion of the steel reinforcing element due to the inherent or the external intrusion of chlorides ions, or the intrusion of other corrosive media, so as to significantly improve the durability of the CFRP-composite structure.
In addition, the entire impressed current cathode protection system for the reinforced concrete structure comprises pre-protected steel reinforcing elements, an auxiliary anode, a DC power detection system and a control system. Within, the major costs of the impressed current cathode protection system are based on the auxiliary anode and the control system, so in order to control the cost of cathode protection system, it is important to develop an optimum auxiliary anode or an improved configuration of the control system. Within, the optimum auxiliary anode is able to achieve by researching the auxiliary anode having a main component of CFRP.
After applying impressed cathode current to the steel reinforcing element, it is needed for testing the corrosion condition of the steel reinforcing element, and measuring electrochemical parameters thereof, such as potential polarization, and the current density of the corrosion, and finally generating feedbacks to the control systems. When the electrochemical parameters of the corrosion condition of the steel reinforcing element does not match the requirements, the control system will regulate the voltage of the DC power supply or the current output thereof, so as to ensure an adequate protection for the steel reinforcing element. Therefore, the traditional impressed current cathode protection system requires expensive in routine maintenance and operation costs.
Therefore, the present invention of the impressed current cathode protection technology needs to be improved.